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Bacteriology > Antibiotics III > Flashcards

Antibiotics III Flashcards

1
Q

Ciprofloxacin (2nd gen.), Levofloxacin, Gatifloxacin and Moxifloxacin all inhibit DNA synthesis and are members of the class of antibiotics known as _____.

A

Fluoroquinolones

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2
Q

What do fluoroquinolones target in G- and G+ organisms, respectively?

A

G- = Gyrase

G+ = Topoisomerase IV

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3
Q

What added constituent of the fluoroquinolones increases their antimicrobial activity

A

Fluorine

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4
Q

Which fluoroquinolone is most effective against G- organisms?

A

Ciprofloxacin

others equal in efficiency, but less than cipro

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5
Q

T/F Cipro is the most effective quinolone against G+

A

FALSE

Cipro is the least effective quinolone against G+ organisms. Others are equal in efficiency, and more effective than cipro.

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6
Q

From least to most, order the quinolones in regard to their actiity against anaerobes.

A

Cipro

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7
Q

What kinds of infections are quinolones used to treat (6)?

A

1) UTI
2) Prostitis
3) GI/Abdominal (Traveler’s diarrhea, Shigellosis, Typhoid)
4) Respiratory (Atypical pneumonias [mycoplasma], S. pneumoniae)
5) Bone/joint/soft tissue (Chronic osteomyelitis, polymicrobial diabetic ulcers)
6) STDs (chlamydia, chancroid)

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8
Q

Which STDs are never treated with fluoroquinolones due to resistance?

A

Syphilis and gonorrhea

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9
Q

Which organisms are beginning to gain resistance to fluoroquinolones (3)?

A

1) S. aureus
2) P. aeruginosa
3) S. marcescens

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10
Q

Which fluoroquinolone is used to treat anthrax and tularemia?

A

Ciprofloxacin

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11
Q

Combinations of fluoroquinolones are used to treat _____ or for _____

A

Atypical mycobacteria or neutropenic prophylaxis

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12
Q

T/F Fluoroquinolone is administered via IV

A

FALSE

Administered orally (can send patients home with it!)

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13
Q

Metronidazole and Nitrofurantoin is under the class of antibiotics known as _____

A

Nitroimidazoles

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14
Q

What is metronidazole’s mechanism of action?

A

Converted to radical iron by ferredoxin, causing fragmentation of DNA

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15
Q

Metronidazole is used to treat _____ and _____.

A

Strict anaerobes (c. diff)

Parasites (trichomonas, giardia, entamoeba)

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16
Q

T/F Metronidazole can’t be used against organisms that use oxygen, including facultative anaerobes

A

TRUE

These organisms have the biological components to deal with free radicals

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17
Q

Nitrofurantoin is used almost exclusively to treat _____ or _____

A

Cystitis or lower UTIs

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18
Q

Nitrofurantoin is effective against many _____ bacteria except _____, AND _____

A

Effective against many GRAM - bacteria except PROTEUS AND PSEUDOMONAS

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19
Q

The sulfonamides function as _____ antagonists

A

Folate antagonists

20
Q

Sulfonamides are competitive inhibitors of _____

A

Dihydropterate synthase

21
Q

The enzyme sulfonamides competitively inhibits (dihydropterate synthase) is needed for the production of _____. Blocking this enzyme prevents the organism from _____.

A

Dihydropterate synthase is needed for the production of THF

Blocking this enzyme prevents the conversion of uracil to thymidine by the organism

22
Q

What are the mechanisms of bacterial resistance to sulfonamides?

A

1) New folic acid pathway
2) Altered affinity of enzyme for drug
3) Efflux

23
Q

Sulfonamides are concentrated in _____, making them _____ in this location

A

Concentrated in urine (great for UTIs!)

Bactericidal there

24
Q

Which sulfonamide is used for opthalmologic infections?

A

Sulfacetamide

25
Q

Which sulfonamide is used to prevent infection and treat infection of burn wounds?

A

Silver Sulfadiazine

26
Q

What are the therapeutic uses of Sulfonamides (4)?

A

1) UTI
2) Nocardiosis
3) PJP (sulfamethoxazole + trimethoprim [bactrim])
4) Toxoplasmosis

27
Q

Rifamycins are _____ spectrum

A

Broad spectrum

28
Q

Which rifamycin is used for HIV+ patients?

A

Rifabutin

29
Q

What are the therapeutic uses of rifampin (3)?

A

1) TB
2) Staph
3) Meningococcus prophylaxis

30
Q

What are the therapeutic uses of ridabutin/rifapentine (2)?

A

1) TB in HIV+

2) MAC

31
Q

T/F Rifaximin is readily absorbed in the gut.

A

FALSE

Rifamixin is limited to the lumen of the gut

32
Q

What is the mechanism of action of rifamycins?

A

Inhibit DNA-dependent RNA polymerase

33
Q

How is bacterial resistance to rifamycins achieved?

A

Alteration of target (DNA-dependent RNA polymerase)

34
Q

What is the mechanism of action of daptomycin?

A

Depolarizes bacterial membrane > K+ efflux > death

35
Q

What kind of organisms does daptomycin cover?

A

Aerobic G+ cocci (except Pneumonias - drug inactivated by lung surfactant)

    - Works against MRSA, MSSA, VRE
36
Q

What is the mechanism of action of Polymyxins?

A

Membrane detergent

37
Q

What kind of organisms do the polymyxins cover? What are the exceptions?

A

G- organisms EXCEPT Proteus, Serratia, Burkholderia

38
Q

Which polymyxin is nephrotoxic?

A

Polymyxin E

39
Q

What are the first line anti-mycobacterium antibiotics?

A

Rifampin
Isoniazid
Pyrazinamide
Ethambutol

RIPE Therapy

(Streptomycin)

40
Q

What are the second line anti-mycobacterium abx?

A 
Cycloserine
Amikacin
Moxi/Gatifloxacin
Ethionamide
Aminosalicylic Aid
Linezolid

CAME to Alleviate Lung

41
Q

Isonazid (INH) prevents the synthesis of _____

A

Mycolic acids

42
Q

Is isoniazid bactericidal or bacteriostatic?

A

Trick question. It’s both.

Bactericidal for growing cells

Bacteriostatic for resting cells

43
Q

Isoniazid (INH) is a prodrug that requires _____ for activation

A

Catalase peroxidase

44
Q

Ethambutl inhibits _____ involved in cell wall synthesis of mycobacterium

A

Arabinosyl transferase

45
Q

Pyrazinamide is bactericidal at _____ pH, as in a macrophage or phagolysozome

A

Acid pH

46
Q

What gene is inactivated by pyrazinamide?

A

Fatty acid synthase I gene

47
Q

Which antimycobacterium drug targets the C subunit of mycobacterium ATP synthase?

A

Bedaquiline (Resistance is acquired by mutating the C subunit)

Bacteriology (19 decks)

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